commodity $
    alias USD

2012-03-12 * $
    A    $10.00
    B

2012-03-12 * USD
    A     15.00 USD
    B

test bal
             25.00 $  A
            -25.00 $  B
--------------------
                   0
end test

test reg a
12-Mar-12 $                     A                           10.00 $      10.00 $
12-Mar-12 USD                   A                           15.00 $      25.00 $
end test

